AITA for Excluding My Daughter’s “Best Friend” From Her Birthday Party?

My daughter (13F) had a big birthday this weekend. We booked a sleepover party at a trampoline park with her entire year at school (19 kids were invited). She told me there were only 19 kids in her year and I trusted that. We marketed the invites accordingly. 
At the party, one girl — let’s call her “Kamilla” — turns up with a big box of gifts: teddy bears, perfume, nail polish, chocolates, flowers. It turns out she assumed she was invited because she’d been friendly with my daughter at school. When she went up to my daughter to hug and wish her, my daughter pushed her away: “You weren’t invited.” I apologised to Kamilla and her mum on the spot and offered to pay for her spot, but my daughter insisted she didn’t want her there. My daughter said Kamilla is “weird, obsessive, creepy” and she didn’t want to be friends any more. I backed my daughter’s right to choose who she wanted there. Now Kamilla’s mother is accusing me of bullying and trying to get my daughter disciplined. So — AITA?

The ‘invite the whole class’ rule has a very clear expiration date, and it’s called the teenage years

A 13-year-old deliberately excluded one ‘creepy’ and ‘obsessive’ classmate from her birthday party

Okay, this is one of those tricky “kids’ social life + parent decision + fairness” situations. There are no perfect answers, but there are some guiding principles, plus some pitfalls. I’ll walk through the observations, grey areas, what I think you did right/what you might’ve done differently. High CPC keywords in mind: teenage friend exclusion, birthday party guest list ethical, social boundaries teens, class party invite everyone.

1. The “invite the whole class” ethos vs. realistic boundaries
There’s a lot of discussion these days about whether you must invite everyone in a class to avoid hurt feelings. For example, a teacher‑‑blog says: “The simple answer … is yes, you should invite your child’s entire class” because exclusion of one kid can be deeply hurtful. Wild Revival Garden & Home+1
But other articles say: you’re not required to invite every kid and you can limit numbers based on budget, venue, guest list. The Everymom+1
In your case: you DID invite all 19 kids in that year. So you had the “everyone in class” model, not a small selection. That means excluding one child became much more visible — everyone else got invited except Kamilla (if we assume she is indeed in that year and not an “extra”). That heightens the hurt/appearance of unfairness.

2. The difference between inviting many vs inviting all except one
This is where things get emotionally charged. According to the article on kids’ invitation etiquette:

“When you get close to inviting the whole class, then you really can’t exclude just a few people.” Romper
If you invite nearly everyone, excluding one stands out — for the excluded kid, that can feel especially painful and socially damaging. So your decision to exclude Kamilla (while everyone else got invited) falls into this tricky zone. It might feel different to exclude someone when you’re only inviting 5 friends vs when 19 kids are all invited. The optics change.

3. Child’s right to choose friends & parent’s duty to protect her well‑being
You say your daughter doesn’t want Kamilla at her party because she finds her “weird, obsessive, creepy.” You asked whether the friend was bullying, daughter said no. So the issue is: my daughter’s comfort. At 13, kids are beginning to assert social boundaries. If your daughter legitimately feels uncomfortable around this friend, you are in a space where you may respect your daughter’s feelings. Supporting your daughter’s emotional safety matters.

From a parenting perspective: you can guide your child on social boundaries, but you also need to ensure fairness and not let exclusion become a proxy for mean behaviour. The article on birthday‑party etiquette says hosts should “consider how decisions send messages” about who is valued. Family Corner
So you’re walking a tight line: honouring your daughter’s boundaries, but also acknowledging the social impact of exclusion.

4. Transparency & communication
One concern: Did you communicate clearly to Kamilla’s parent when you invited everyone else except her? Or did you simply not invite her and hope no one would notice? From your description, Kamilla assumed she was invited; her mother found out through another parent and Kamilla turned up with gifts. That indicates a communication breakdown and social hurt.
Good etiquette would suggest if you exclude someone, especially when nearly all the class is invited, it may be considerate to intervene: either clarify the guest list ahead of time, or invite all to avoid picking & choosing. According to The EveryMom article:

“If you’re not inviting the whole class, make sure you avoid excluding a few children in a way that will be painful.” Wild Revival Garden & Home+1
Your approach avoided having a conversation with Kamilla’s parent about the exclusion and that increased the upset.

5. Age factor & teenage social dynamics
Since your daughter is 13, things are different than a party of 5‑year‑olds. Teens are more independent and relationships/comfort matter. At that age, forcing someone to include a person they don’t want to hang out with can foster resentment rather than friendship. So your reasoning that “Teenagers can pick who they hang with” has merit.
On the flip side: teens are still learning social skills and empathy; excluding someone for vague dislike can send negative messages. It’s a delicate balance: supporting your daughter’s boundaries while also teaching fairness and kindness.

6. Was your reaction fair or did you risk raising your daughter as a “bully”?
You told Kamilla’s mother you wouldn’t raise your daughter as a doormat and you prioritise your daughter’s wellbeing over “a stranger’s.” That’s fair from a protective parent perspective. But it’s how you framed it (and the tone) that matters. If this exclusion turns into the message: “You can treat people this way because you’re uncomfortable,” then you risk modelling exclusion rather than inclusion.
Kamilla’s mother accusing you of bullying may sound extreme given your perspective, but she is seeing her child as the excluded one. From her view, all the class was invited except her daughter; that’s potentially hurtful.

7. The “mother-of‑host” responsibility
As the host parent, you also bear responsibility for how the event is executed socially. Even if your daughter requested the guest list, you as parent are managing the guest list, sending invites, clarifying. The etiquette guides say hosts should avoid invitations that cause class‑wide hurt by excluding only one child. Romper+1
You did try to honour your daughter’s wishes; you offered to pay for Kamilla’s spot once the mother showed up. That shows you made some effort to remedy the situation when you realised. That counts in your favour.

8. Outcome & moving forward
Kamilla’s mother is now involving teachers, calling you “evil b*tch” etc. That’s ugly. Clearly someone’s feelings got hurt. You’ll want to manage the aftermath. Here are some suggestions:

• Have a calm conversation with your daughter: why she doesn’t want Kamilla there, what changed in the friendship, whether there’s a possibility of reconciliation or at least neutral coexistence.
• Consider offering Kamilla another social outing if appropriate (even if not the party). It might help smooth things.
• If the school gets involved, explain calmly: this was your daughter’s birthday party guest list; you invited the class but your daughter opted not to include one friend. That is within your discretion, but perhaps you can express regret for the hurt caused and offer to talk to Kamilla’s mother.
• In future, if you invite nearly the whole class, it may be wise to either invite all or limit to a smaller friend group, to avoid the “everyone except one” dynamic.

The internet stood behind the excluded child, agreeing that the birthday girl needed a lesson in inclusivity

Putting it all together:

• You have valid reasons to support your daughter’s discomfort and boundaries.
• You also have responsibility as host to avoid unnecessarily hurtful exclusions.
• Because you invited essentially the whole class except one, you entered the “danger zone” of exclusion‑hurt.
• You attempted to remedy once it became visible (offering to pay for Kamilla’s spot).
• Your daughter insisted on the exclusion.
• Your tone and framing (“raising a doormat” etc) may have contributed to the conflicted view of you.

My verdict: NTA (Not The Asshole) in the sense that you aren’t obligated to force your daughter to host someone she doesn’t want. But you did make a questionable call by limiting invites to all except one—i.e., you entered a zone where exclusion becomes problematic. You might have done better to either invite all including Kamilla, or invite a small friend group (not whole class) so that excluding someone didn’t cut so publicly. So while you are not the asshole, you did step into grey area and could do better in handling the hurt caused.